This invention relates to paperboard containers in general, and in particular to an improved hermetic closure for paperboard containers.
Paperboard containers are now being used to package a wide variety of organic products, especially processed foods. These containers must be siftproof, stackable, and resistant to air, liquids, and insect infestation. Packages which are to be sold in supermarkets should also be sturdy and pilfer-proof, and have a relatively long shelf life.
The packages most commonly used to meet these requirements have been multi-layer containers consisting of a paperboard box and a flexible sheet of hermetically sealable material. The flexible sheet has been used either as a liner for the box, as in French Pat. No. 1,247,747, or as an overwrap for it. Single-layer coated paperboard containers, though less expensive and easier to manufacture, are seldom seen outside the dairy case due to the difficulty of making a closure which is both hermetic and flat enough to be stackable.
It is therefore an object of the present invention to provide a hermetic closure for a paperboard container.
It is another object of the present invention to provide a novel low-cost paperboard container which is sift-proof, pilfer-proof, air resistant, durable and resistant to infestation by insects.
It is yet another object of the present invention to provide a paperboard container with a long shelf life and superior stacking strength.